Cushioning device

ABSTRACT

A block of elastomeric material provided with at least two sealed internal cavities interconnected by a duct means is operatively interposed between two relatively movable bodies, so that distortion of said block causes same to be locally compressed around one of said cavities and locally stretched around the other cavity whereby a liquid filling said cavities and said duct means is forced to flow through the latter which is provided with throttling means operative for impeding the flow of said liquid.

United States Patent Andre Alired Malherbe 81,rue Pasteur 59, Waziers, France 861,007

Sept. 25, 1969 Oct. 12, 1971 Sept. 25, 1968 France lnventor Appl. No. Filed Patented Priority CUSHIONING DEVICE 10 Claims, 7 Drawing Figs.

US. Cl 267/ 152 Int. Cl 860s 11/22 Field of Search 267/ 140,

[5 6] References Cited UNITED STATES PATENTS 2,226,605 12/ l 940 Geyer et al. 267/35 3,087,717 4/1963 Jewell 267/35 Primary Examiner-James B. Marbert Attorney-Nolte and Nolte ABSTRACT: A block of elastomeric material provided with at least two sealed internal cavities interconnected by a duct means is operatively interposed between two relatively movable bodies, so that distortion of said block causes same to be locally compressed around one of said cavities and locally stretched around the other cavity whereby a liquid filling said cavities and said duct means is forced to flow through the latter which is provided with throttling means operative for impeding the flow of said liquid.

Q PATENTEDHBHZISYI 1 ,5 5

sum 10F 3 914% i 5'14; Arlmwm CUSHIONING DEVICE The present invention generally relates to devices for cushioning the relative displacement of two bodies and is more particularly concerned with such a device adapted to damp down the relative oscillation of two bodies connected by an articulated link, such as a tractor and trailer assembly.

Numerous devices are known in the art, which are adapted to damp the relative motion of two bodies; in such devices, mechanical energy is usually converted by frictional effects into thermal energy, which is easily dissipated; in many occurrences, the aforesaid conversion is effected through fluid friction, by using the relative displacement of the two bodies to force a liquid through a throttle. It is thus possible to obtain an important energy dissipation by means of a device having a small bulkiness and which is substantially devoid of wear.

However, most of the fluid-friction-cushioning devices include piston and cylinder assemblies, the manufacture of which is costly because of the small fitting tolerances being required for an efficient sealing action, and which are further easily damaged by wear and accordingly put out of service, if expensive treatments and/or costly materials are not used for their manufacture.

A first object of the present invention is to work out a cushioning, device of rugged structure and small overall dimensions, built from simple elements and devoid of any piston and cylinder assembly, which is thereby easily manufactured at low cost and requires no maintenance.

, To this end, a cushioning device madein accordance with the present invention is characterized notably in that it is essentially comprised of a block of elastomeric material adapted to bedistorted and notably to be in part compressed and pan stretch-by the aforesaid relative motion, said block being formed by a pair of internal sealed cavities arranged so .that their respective volumes vary inversely during the block distortion, said cavities being connected by at least one duct means provided with throttle means adapted to impede the transfer between said cavities of a liquid with which they are it will be clearly seen that the invention allows for the con struction of cushioning devices of various configurations, in which energy is dissipated not only by throttling the liquid being transferred which action is particularly efficient with respect to important overall deformations of the block, but also by internal friction within, the block of elastomeric material which action is particularly efficient with respect to short-range and fast deformations of said block. Besides, all

, the structural elements of the device can be incorporated to the block of elastomeric material, so that the possible uses of the device are not limited by sealing constraints; in this respect, it should be noted that the device being distorted keeps a constant volume, and thus is not affected by the ambient pressure, whereby it can be used without constraint in variable pressure environment, and by way of example for submarine uses. ln addition, the device works silently.

According to another characteristic feature of the device of this invention, the aforesaid block of elastomeric material is compressed between two rigid end plates, which are for example parallel at rest, and driven into relative angular displacement by the aforesaid motion.

Of course, said end plates can be incorporated to the device itself, and can carry fastening means providing for its universal use or conversely could form integral parts of the bodies, the relative motion of which is to be damped down by said device.

According to further characteristic features of the device of this invention, the center portions of the aforesaid end plates are connected to one another by a nonstretchable tie member, which is flexible and/or hinged with at least one of said end plates, and which advantageously extends through the block of elastomeric material.

The so-constructed device has for an advantage to constitute a functionally complete unit, adapted to provide for mutual linkage between the bodies in addition to the cushioning of their relative motion, and possibly for the transmission between said bodies of compression or twist forces, and further of traction forces.

According to still further characteristic features of the device of this invention, the aforesaid cavities are formed on either side of the aforesaid non stretchable tie member extending through the block of elastomeric material; when the .latter is formed with several cavities; said cavities are distributed around said tie member according to a cyclic pattern.

The above-mentioned features have for an obvious advantage to allow for the construction of a cushioning device having a balanced geometrical structure, and more particularly of a device adapted to damp down a swivel motion about a fulcrum.

The aforesaid block of elastomeric material can be formed with several pairs of cavities disposed at respective diametrically opposite locations with respect to the aforesaid tie member and connected to each other by a respective duct means, thereby allowing for selective cushioning of angular motions occurring around axes respectively perpendicular to the planes of said pairs of cavities.

The aforesaid duct means connecting the cavities are advantageously provided with throttle members, possibly bypassed by valve means having a larger flow rate, which open for a determined direction of liquid flow and/or under a determined differential pressure.

This arrangement permits to-obtain at will a double-throw cushioning effect having identical or different intensities in either direction of liquid flow, and in the borderline case, a single-throw cushioning effect, whilst avoiding if required any risk of overpressure liable to cause damage to the device. The rating of the throttle member, and possibly that of the valve means, if preferably adjustable.

Other features and advantages of the device according to this invention will appear more clearly when reading the following description of several illustrative embodiments shown in the accompanying drawings, in which:

fig. 1 illustrates a possible use of a device made in accordance with the invention for coupling a trailer to a tractor vehicle.

FIGS. 2A, 2B and 2C are diagrammatic sketches illustrating the structure and working of a device according to the invention.

FIG. 3 is a perspective, part-sectional view of a device constituting an illustrative embodiment of the invention, and

FIGS. 4 and 5 show two possible uses of the cushioning device of FIG. 3.

FIG. 1 illustrates the use of a cushioning device D according to the invention for coupling a caravan C to a tractor vehicle, such as a car A; the device D, as shown from the outside, is essentially made of a block of elastomeric material E disposed between two end plates F, one of which is secured with bolts to the pole T of the caravan C and the other of which carries an axial pin fitted into a sleeve M rigid with the tractor vehicle A, said pin being locked in position by the grasp of 'a pawl carried by said sleeve into a peripheral groove formed in said pin.

The device D is capable of transmitting to the caravan C the traction exerted by the car A while cushioning the sway and pitch motions of said caravan, the roll motion of which is however independent from that of the car A, owing to the arrangement of the coupling between the device D and the sleeve M. These properties of device D derive directly from its internal structure, which is clearly illustrated by the sketches of FIGS. 2A-2C. 7

As shown on FIG. 2A, the center portions of the end plates F between which the block of elastomeric material E is compressed are connected to one another by a nonstretchable tie member L, comprising by way of example a tie rod hinged with one of the end plates F by means of a swivel joint, or conversely a cable or chain stretched between the end plates, so that the latter are held in a predetermined spaced relationship, but can freely rotate with respect to one another, as shown on FIGS. 28 and 2C; in the illustrative use of the device shown on FIG. 1, this arrangement obviously permits to transmit the traction force of the car A to the caravan C, while allowing for free orientation of the latter.

The block of elastomeric material E is substantially of cylindrical shape and is formed by four internal cavities El-E4 symmetrically distributed around a central cavity EO through which extends the nonstretchable tie member L; cavities El and E3, which lie in the same vertical plane, are sealingly closed and connected by a duct R provided with an adjustable throttling valve S bypassed by a one-way valve S. Similarly, cavities E2 and E4, located in the same horizontal plane and accordingly not shown on FIGS. 2A-2C, are sealingly closed and connnected by a duct provided with an adjustable throttling valve. The cavities El-E4, as well as their connecting ducts and associated valves, are filled up with a liquid, the included air being carefully drained.

The working of device D follows obviously from its structure; any relative angular displacement of the end plates F distorts the block of elastomeric material B, one part of which is compressed, and the diametrically opposite part of which is stretched; accordingly, the capacity of the cavity located in the compressed part and the capacity of the cavity located in the stretched part vary inversely, the first being reduced while the second increases, and are modified by the same amount, since the elastomeric material keeps its volume constant when it is distorted, and since the liquid filling up the cavities is incompressible. Thus, a given amount of liquid is transferred from the first to the second cavities, the displacement of which is impeded by the throttling valve inserted in the duct connecting said cavities to one another; of course, the restriction of the flow of the liquid causes a force to be developed which tends to impede the deformation of the block of elastomeric material E and accordingly to cancel the external force which tends to distort said block.

In the illustrative use of the device shown in FIG. 1, the cavities E2 and E4 lying in the same horizontal plane are connected by means of a mere throttling valve, whereby the sway movements of the caravan in either direction are identically damped down; on the contrary, the throttling valve S through which the cavities E1 and E3 lying in the same vertical plane are interconnected is advantageously bypassed by a one-way valve, whereby the pitch movements of the caravan are damped down in an asymmetrical manner, the device D impeding efiiciently any raising movement of the pole T, but on the contrary having substantially no effect against its downward displacements, as it is shown on FIGS. 28 and 2C respectively.

Obviously, the structure of the device D and its mounting between the car A and the caravan C could be modified whenever required; particularly, if it is desirable to keep unaltered the original coupling, the device D could be affixed laterally to the caravan C or to its pole T by one of its end plates, the pin carried by its other end plate engaging with a sliding fit through an eyepiece or sleeve secured by a toggle joint to the corresponding side of the tractor vehicle A. In this last occurrence, an asymmetrical damping of the sway movements could be provided for, with a view to compensating the difference of the lever arms in either direction of relative rotation of the caravan c, and/or to taking into account the cambering of the roadway.

F IG. 3 illustrates in a more realistic way than the sketches of FIGS. 2A-2C a possible embodiment of the device D shown on FIG. 1.

In the block of elastomeric material E, which is of substantially cylindrical shape, are included; a metal strip which is helically wound on its flats to constitute a resilient stiffener for cavity EO; four bellows ll, 12, 13 and 14 made of rubber-impregnated fabric and substantially inextensible in peripheral direction, respectively define the cavities El, E2, E3 and E4; a stiffening structure for the outer periphery of the block, which consists of a braid of metal or textile yarns wound helically on its flats; and at last the valves 51,3 and 82,4 which respectively connect ducts R1, R3 extending from bellows ll, 13 to ducts R2, R4, extending from bellows l2, 14. The manufacture of the block E can be easily proceeded with by putting along the axis of a cylindrical mould the central stiffener l0 surrounded by a sleeve of crude elastomeric material and by wrapping on the inner periphery of the mould the braid l4 embedded in crude elastomeric material, then by placing between the stiffeners the bellows 11 to 14 and their connecting ducts, together with the valves 81,3 and 82,4 interconnected with the latter, said bellows being advantageously swelled with compressed air and held in place by temporary fixtures in order to facilitate the last-mentioned operation, and finally by pouring into the so-fitted mould, elastomeric material in the form of a latex, an emulsion, a powder or any other suitable form and curing the whole body of material to cause the same to cohere and to acquire the required properties.

The end plates F1, F2 merely consist of stamped sheet metal blanks 20, identically shaped and formed with an outer turned edge, in the center of which are secured, as by welding, respective sleeves 21, 22. The end plates F 1, F2 are laid upon the end faces of the block of elastomeric material E, and are preferably cemented thereto, their sleeves 21, 22 are fitted in the central cavity E0, whereas their outer turned edges are advantageously crimped over the periphery of the block in order to provide for proper centering of the latter and for stiffening the assembly.

The cavities E1-E4 and their connecting ducts Rl-R4 are then filled up with a liquid and carefully drained, if this operation was not effected when casting the block of elastomeric materials E; to this end, it is convenient to lay aside the metering screws provided for adjustment of the throttling valves 81,3 and 82,4 which extend through holes formed for this purpose in the end plates F l F2.

Now, the last operation is to insert through the central cavity E0 the nonstretchable tie member (not shown) connecting the end plates F 1, F2 said tie member consisting either of a cable or chain anchored on fixtures rigid with the sleeves 21, 22, or of a stiff tie rod rigidly secured to one end plate and hinged with the other by a toggle joint. Whatever the nature of the tie member may be, means are advantageously provided for enabling its tensioning, with a view to exerting a predetermined compression on the block of elastomeric material E and thus preventing its stretched portions from being torn when it is distorted; of course, during this tensioning, a determined amount of the liquid filling up the cavities E1 to E4 must be allowed to escape, by way of example, through partial unscrewing of the setting screws of the throttling valves 81,3 and 82,4.

The device D being thus completed may be mounted in operative position and for instance secured to the pole T of the caravan C shown on FIG. 1 by means of studs rigid with the end plate Fl, a suitably shaped pin being mounted in and extending axially outwards from the sleeve 22 rigid with the end plate F2 for this same intended use.

FIGS. 4 and 5 illustrate two other possible uses of the device D made in accordance with the embodiment shown on FIG. 3.

On FIG. 4 is shown in elevation with local section a railway car W provided with a pendular or "state car" suspension system including cushioning devices made in accordance with the invention. The bolsters of the carriage in which are journaled the wheel axles carry, through the intermediary of the primary and secondary suspension stages, a footplate P rigid with a post P, the upper end of which supports the body of the car W through the intermediary of a swivel joint. This construction allows not only for free rotation of the carriage under the car body, but also for lateral slanting of said body when the car runs at high speed along a curved track in order to compensate the effects of centrifugal force; however, guide means prevent longitudinal displacements of the carriage under the car body, by way of example as they occur during a deceleration caused by braking.

The rotation of the carriage and the slanting of the body, and thus the sway and roll motions, are damped down by means of two cushioning devices D1, D2 made in accordance with the invention. These devices are secured to the body of car W in its longitudinal median plane, on either side of the post P, and carry each a pin which extends through an aperture formed to this end in the footplate P of the carriage. It will be seen that the devices D1, D2 are distorted in opposite directions when the carriage rotates, and in the same direction when the body slants, and accordingly can efiiciently cushion these motions without interfering with the normal movements of the carriage.

FIG. 5 illustrates another possible use of the device according to the invention, namely the suspension of a centrifugal dryer comprising a framework B in which spins a drum T driven into rotation by a motor M rigidly secured to the framework; the latter is carried, through the intermediary of toggle joints, by three cushioning devices D1, D2 and D3 according to the invention, disposed symmetrically about the vertical axis of revolution of the drum T. It will be seen that this construction allows for an efficient damping of the radial motions deriving from a possible want of balance of the drum T or of its content, and also of the peripheral motions occurring when the drum starts to rotate or is braked; the cushioning of these motions can be possibly different.

Of course, the invention is not limited to the embodiments shown and described, which are only illustrative, and on the contrary includes all modifications and adaptations of the device remaining within the skill of the technicalman; thus and for instance, it is possible to build a device having a circular, symmetry around an axis, including by way of example three cavities each one connected to the two adjacent cavities by ducts provided with throttling means; said throttling means could consist, instead of independent valves, of particular configurations of the ducts, such as internal lips forming a reed corresponding to a throttle and associated one-way valve; the device could be symmetrical with respect to a plane including the axis of relative rotation of its end plates and on either side of which could be located mutually interconnected cavities; said end plates could be connected to one another by a stiff, nonstretchable tie member hinged with one end plate in a manner allowing for transmission of compressive forces; the end plates themselves could be omitted, the block of elastomeric material being directly cemented to the surface of two relatively moving bodies, for instance in a machine-tool or in a suspension system. In addition, the invention includes all means technically equivalent to those shown and described, as well as their combinations, carried out in accordance with the gist of the invention.

What is claimed is:

l. A device for cushioning a relative motion of limited amplitude between two bodies, such as relative oscillation of said bodies, said device being comprised of an integral block of elastomeric material operatively connected to said bodies, to be distorted by said motion without changing its overall volume, so that one part of said block is compressed while another part of same is stretched, said block being formed with at least two sealed internal cavities respectively located in said parts and arranged so that their volumes vary inversely as a consequence of the block distortion, said cavities being interconnected by at least one duct means, said cavities and said duct means being filled with an incompressible liquid, and said duct means being provided with throttle means operative to impede the transfer of said liquid between said cavities during said block distortion.

2. Device according to claim 1, characterized in that said block of elastomeric material is disposed between two rigid end plates operatively connected to said bodies and which are driven into relative angular displacement by the aforesaid relative motion.

3. Device according to claim 2, characterized in that the center portions of said end plates are connected to one another by a nonstretchable tie member, which is flexible and/or hinged with at least one of said end plates.

4. Device according to claim 3, characterized in that said nonstretchable tie member extends through said block of elastomeric material.

5. Device according to claim 4, characterized in that the aforesaid cavities are located on either side of a plane, in

which said nonstretchable tie member extends.

6. Device accordlng to claim 4, characterized in that said block of elastomeric material includes several cavities symmetrically distributed around a common axis and operatively interconnected by respective duct means along which extends said nonstretchable tie member.

7. Device according to claim 4, characterized in that said block of elastomeric material includes several pairs of cavities disposed at respective diametrically opposite locations with respect to a common axis along which extends said nonstretchable tie member, the cavities of each pair being connected to one another by a respective duct means.

8. Device according to claim 1, characterized in that said throttling means are bypassed by valve means opening for a determined direction of liquid flow under a determined differential pressure.

9. Device according to claim 8, characterized in that the flow rate of said throttling means and/or valve means is adjustable.

10. Device according to claim 3, characterized in that said block of elastomeric material is of substantially cylindrical shape and is compressed between two circular end plates, the center portions of which are connected to one another by a nonstretchable tie member extending axially through said block, said block being formed with two pairs of sealed internal cavities disposed in respective perpendicular axial planes and interconnected by respective duct means including respective throttling means. 

1. A device for cushioning a relative motion of limited amplitude between two bodies, such as relative oscillation of said bodies, said device being comprised of an integral block of elastomeric material operatively connected to said bodies, to be distorted by said motion without changing its overall volume, so that one part of said block is compressed while another part of same is stretched, said block being formed with at least two sealed internal cavities respectively located in said parts and arranged so that their volumes vary inversely as a consequence of the block distortion, said cavities being interconnected by at least one duct means, said cavities and said duct means being filled with an incompressible liquid, and said duct means being provided with throttle means operative to impede the transfer of said liquid between said cavities during said block distortion.
 2. Device according to claim 1, characterized in that said block of elastomeric material is disposed between two rigid end plates operatively connected to said bodies and which are driven into relative angular displacement by the aforesaid relative motion.
 3. Device according to claim 2, characterized in that the center portions of said end plates are connected to one another by a nonstretchable tie member, which is flexible and/or hinged with at least one of said end plates.
 4. Device according to claim 3, characterized in that said nonstretchable tie member extends through said block of elastomeric material.
 5. Device according to claim 4, characterized in that the aforesaid cavities are located on either side of a plane, in which said nonstretchable tie member extends.
 6. Device according to claim 4, characterized in that said block of elastomeric material includes several cavities symmetrically distributed around a common axis and operatively interconnected by respective duct means along which extends said nonstretchable tie member.
 7. Device according to claim 4, characterized in that said block of elastomeric material includes several pairs of cavities disposed at respective diametrically opposite locations with respect to a common axis along which extends said nonstretchable tie member, the cavities of each pair being connected to one another by a respective duct means.
 8. Device according to claim 1, characterized in that said throttling means are bypassed by valve means opening for a determined direction of liquid flow under a determined differential pressure.
 9. Device according to claim 8, characterized in that the flow rate of said throttling means and/or valve means is adjustable.
 10. Device according to claim 3, characterized in that said block of elastomeric material is of substantially cylindrical shape and is compressed between two circular end plates, the center portions of which are connected to one another by a nonstretchable tie member extending axially through said block, said block being formed with two pairs of sealed internal cavities disposed in respective perpendicular axial planes and interconnected by respective duct means including respective throttling means. 